As environmental agencies become more aware of the potential health risks associated with using either municipal or well water in sterile environments such as dental offices, there has been an every increasing need for water purification systems which are capable of removing organics, inorganics, particulates, microorganisms, bacteria and viruses from the water supply prior to use on or in the patient. Most conventional filtration systems require a series of filtration and chlorination units to properly remove such matters from the water. These units are extremely costly to install and maintain, and take up a lot of space making them unfit for use in dental offices.
Filtration media have been used for years to remove particulates from the water supply, while carbon block filters have been effective in removal of organics and inorganics. However, conventional filters are incapable of removing microorganisms such as bacteria, viruses, yeasts or molds. Ultraviolet radiation in the 200-300 nanometer range have been extremely effective in killing such microorganisms. As such, germicidal lamps have been used extensively in air and water purification, sewage treatment, protection of food and beverages, and other disinfecting and sterilization applications.
Recent efforts by filtration manufacturers have resulted in the creation of a water purification system which combines the disinfecting and sterilization capabilities of ultraviolet radiation with the particulate, organic and inorganic filtering capabilities of conventional filter media. This combined system provides extremely pure and sterilized, purified, water regardless of the origin of the water source.
These conventional two stage water purification systems typically include an ultraviolet lamp affixed to the base unit of a filtration housing assembly and protected by a stainless steel sheath or sleeve. A conventional carbon block filter is removably slid over the outside of the sleeve and then the filter housing is placed over the carbon filter and screwed into the base. Typically, the ultraviolet lamp is placed within a quartz tube and replaceably mounted to the base.
One major problem with the use of any filtration system in dental offices is the formation of biofilm. In The New York State Dental Journal, December 1995, Vol. 61, No. 10, issue it was stated that "We believe the only way to lower bacterial counts in the water that feeds handpieces to acceptable levels is to eliminate the biofilm and prevent its return."
A network of small diameter water lines used in feeding dental handpieces and air-water pistols can become coated with a fine layer of bacteria called a biofilm. This biofilm forms naturally as a result of stagnation of contaminated water inside these small, flexible tubes. The adherence of certain species is facilitated by microscopic imperfections on the internal surfaces of the water lines which allow bacterial adsorption and which in turn initiates the formation of the biofilm.
The closely packed bacteria are held in place by a matrix of polysaccharides and glycoproteins. The attached bacteria, which are not easily flushed out, proliferate and produce a matrix, which in turn allows the establishment of other species of bacteria. The biofilm becomes populated with a greater and greater variety of bacteria; it also protects the bacteria during their growth by retaining nutritional material and by allowing a higher level of metabolic activity, all the while protecting the bacteria from biocidal substances. The biofilm gradually becomes visible to the naked eye and can eventually partially obstruct the lumen of the water line.
The conventional way of eliminating biofilm is to fill the water lines with a disinfectant at the end of each day, allowing over-night treatment of the water lines. At the beginning of the day the disinfectant is drained and water flows through cleaned water lines. This avoids contact of the disinfectant with the patient and allows the regular water supply to be used in the dental unit. Although this form of treatment is generally effective, over time, biofilm begins to form in the crevices of the tubing and cannot typically be removed by treatment with disinfectants. Furthermore, the use of disinfectant is both costly and time consuming. Also, there is a potential risk that a portion of the disinfectant cannot be removed from the lines and is transported to the dental handpiece and into the patient's mouth.
The unique system according to the present invention provides an extremely inexpensive and efficient means for removing particulates, organic materials, inorganic materials, heavy metal materials, microorganisms, bacteria and viruses contained within an aqueous liquid, for example, water, supplied to a dentist's water supply system, while also eliminating the formation of biofilm in the tubes used to carry water to the dental units or handpieces. The present invention preferably accomplishes this by providing a filtration and/or sterilization, i.e., purification system which preferably includes both an ultraviolet water filtration and sterilization unit in conjunction with means for contacting the filtered and/or sterilized, i.e., purified aqueous liquid, e.g., water, with at least about 0.2 wt. % of an oxygen solution.
The present invention also provides many additional advantages which shall become apparent as described below.